Hey dude! nice rmt, here's my suggestions:

First of all Landorus-T Salac Berry is a pretty nice set but a bit hard to setup so I suggest another spread 48 HP / 252 Atk / 208 Spe Jolly nature, I made this spread because you don't really need to play your Landorus-T full speed at the beginning I consulted the ORAS Speed Tiers to see who Lando-t can outspeed with the Salac Berry and without, so this spread allows it to outspeed Hydreigon LO and also it allows to outspeed Alakazam-Mega, Aerodactyl-Mega and Hydreigon Scarf after the Salac Berry's boost, the remaining EVs I put them in HP for more bulk.

For Azumarill, such as you said you want to outspeed Venusaur-Mega so I made this spread 60 HP / 252 Atk / 196 Spe Jolly nature with 203 Speed you can outspeed it, HP's EVs activate the Sitrus Berry if you use Belly Drum don't worry

Alakazam Sash ain't bad yes but in your team the LO will be better, also remove Thunder Wave on Zam because the "threats" of your team as you said in the threatlist and Alakazam set are immunite to Electric-Move except Serperior, I suggest the LO Alakazam set because it can help you for some pokemon who annoy your team and that you have some difficult to kill principaly as Mega-Venusaur, Slowbro, Quagsire  so the LO set will be help you a lot.
[hide=Alakazam Set]
Alakazam @ Life Orb
Ability: Magic Guard
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Psychic
- Shadow Ball
- Focus Blast
- Encore/Taunt/Recover/Calm Mind[/hide]

Finally Slowbro, you wanted to able to take a Thunderbolt from Manectric and Raikou at +1 and take at +2 a Thundurus Tbolt and Gengar Shadow Ball? I made again a spread 252 HP / 28 Def / 228 SpD  that one with 228 EVs Speed is alsmost the same that 252 EVs on the calc. the remaining EVs in Def for more bulk.

[hide= Some calcs]
252 SpA Mega Manectric Thunderbolt vs. +1 252 HP / 228+ SpD Slowbro: 170-204 (43.1 - 51.7%) -- 7.4% chance to 2HKO
252 SpA Raikou Thunderbolt vs. +1 252 HP / 228+ SpD Slowbro: 152-182 (38.5 - 46.1%) -- guaranteed 3HKO
252 SpA Choice Specs Raikou Thunderbolt vs. +2 252 HP / 228+ SpD Slowbro: 174-206 (44.1 - 52.2%) -- 16% chance to 2HKO
252 SpA Life Orb Gengar Shadow Ball vs. +1 252 HP / 228+ SpD Slowbro: 195-229 (49.4 - 58.1%) -- 95.3% chance to 2HKO
252 SpA Life Orb Gengar Shadow Ball vs. +2 252 HP / 228+ SpD Slowbro: 148-174 (37.5 - 44.1%) -- guaranteed 3HKO
252 SpA Life Orb Thundurus Thunderbolt vs. +2 252 HP / 228+ SpD Slowbro: 159-190 (40.3 - 48.2%) -- guaranteed 3HKO[/hide]

Hope I helped and good luck with your team. :p